Association‐Dissociation Behaviour and Hydrodynamic Properties of Apoferritin Monomer and Dimer

The association behaviour of a homogeneous preparation of apoferritin has been investigated. Contrary to studies by other authors on less pure material, no evidence for a reversible association of the protein was detected in sedimentation equilibrium, light scattering or sedimentation velocity experiments. Correspondingly, no dissociation of an isolated dimer of apoferritin was observed. Hydrodynamic parameters, such as frictional ratio and intrinsic viscosity, indicate that both apoferritin monomer and dimer have a somewhat larger degree of hydration or a slightly more extended or irregular shape than most typical globular proteins. The solvent, presumably trapped inside the protein shell, cannot alone account for this behaviour.